• Journal of Korean Society of Water and Wastewater
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• v.22 no.3
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• pp.389-396
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• 2008

The hybrid model can be used to predict the initial near field mixing and the far field transport of the buoyant jets, which are discharged from the submerged wastewater ocean outfall. In the near field, the jet integral model can be used for single port diffusers while the ${\sigma}$ transformed particle tracking model was used in the far field. In this study, the experimental study was performed to verify the developed hybrid model in the previous research. The developed hybrid model properly predict the surface and vertical concentration distribution of the single buoyant jets with various effluent and ambient conditions. The hybrid model can also simulate the surface concentration distribution of the rosette diffuser except for the parallel diffuser with the higher densimetric Froude number due to the assumption that dynamic effects of the effluent plumes are negligible in the far field. The application of the hybrid model to rosette diffusers can predict the concentration near the diffuser more accurately when the line-plume approximation is used.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.389-389
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• 2023

우리나라는 농업 산업화의 발달로 인하여 농업용수, 공업용수, 생활용수 사용이 증가하며, 하천에서 직접 물을 취수하여 사용하고 있고 이용 후 생활용수, 농수로 등을 통해 회귀되는 유량이 많아 하천의 유출 특성을 파악하는데 어려움이 있다. 따라서 정확한 하천 유출 체계 특성을 파악하기 위해서는 하천에서 사용되는 물의 이용 특성에 대하여 파악할 필요가 있다. 본 연구에서는 길안천에 운영되고 있는 취수 시설에 대해 문헌조사와 현장조사를 진행하였으며, 조사한 자료를 토대로 하천의 물 사용 체계 모식도를 작성하였다. 길안천 유역의 조사 구간은 대사3교 하류에서 구)묵계교 상류까지 조사를 실시하였다. 문헌조사 대상시설은 취입보, 취수장 등이며, 조사대상은 하천의 유출특성에 영향을 줄 수 있는 시설로 길안천 유역에 영향을 주는 시설에 대해서만 수행을 하였다. 현장조사에서는 현장을 방문하여 취⋅배수시설의 위치 등을 조사하였다. 길안천은 농업용수와 생활용수 사용의 증가에 따라 상하류 측정유량의 반전이 빈번하게 발생하였으나 유출체계 분석을 통해 고려한 결과 안정적인 상하류 관계를 확인하였다. 결과적으로 본 연구를 통해 하천 내 취⋅배수시설 영향에 따른 유출 특성을 고려하여 자료를 검토한 결과 길안천 유역 내의 상하류 유량 반전 시기가 과거에 비해 감소하였으며, 안동시(대사3교)관측소와 안동시(묵계교)관측소 구간의 취⋅배수영향을 고려하여 산정한 유출률을 기존자료와 비교한 결과 일정한 손실고가 유지되는 안정적인 결과를 도출하였다.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.6
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• pp.833-842
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• 2009

A series of laboratory experiments has been performed to investigate the behaviour of interfacial layer of saltwater wedge in estuary. Experimental conditions have been established according to densimetric Froude number, which is a dimensionless number comparing inertia force with buoyancy due to the density difference. To observe the behaviour of saltwater wedge, conductivity meter has been used to detect salinity. Time averaged and temporal variation of observed properties have been analyzed to determine and investigate the interfacial layer. The location and profile of interfacial layers have shown the dependency on densimetric Froude number. The thickness of interfacial layer has been also dependent on the variation of densimetric Froude number.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.6
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• pp.825-832
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• 2009

A series of laboratory experiments has been performed to investigate the flow characteristics of 2-dimensional density currents induced by selective withdrawal, which is commonly suggested as a measure for removal of high turbid water from reservoirs. Saltwater has been used to simulate the density stratification over depth and PIV(Particel Image Velocimetry) for observing the velocity structure. Experimental conditions have been established according to Richardson number, which is the dimensionless number that expresses the ratio of potential to kinetic energy. From the experiments, the patterns of longitudinal decay of centerline axial velocity induced by the withdrawal have been distinguished from other experimental cases. The rate of longitudinal decay increase as the Richardson number increases. The variations of volumetric and momentum flux along the longitudinal axis have also shown to be dependent on Richardson number.

• Journal of Korean Society of Water and Wastewater
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• v.12 no.3
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• pp.65-74
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• 1998

Life cycle assessment (LCA) on two different sludge treatment systems, on-site treatment and pipe-collected intensive treatment was performed to estimate the environmental impact in the aspect of global warming effect. As a main parameter of the estimation, $CO_2$ was chosen and quantified through the whole life cycle of the treatment systems including construction, operation and dismantlement. In this study, the changes of $CO_2$ production unit (CPU) by up-scaling n currently used sludge treatment processes were also calculated. As the result, a larger amount of $CO_2$ was exhausted from the construction step of intensive treatment system than that of on-site treatment system, because an additional pipe-collection system was needed in intensive treatment system. However, the total amount of $CO_2$ exhausted from whole life cycle including not only construction and dismantlement but also 15 year-operation and maintenance was reduced by appling intensive treatment.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.1
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• pp.85-95
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• 1996

Although the specific resistance to filtration is the most frequently employed means for characterizing dewaterability of a sludge, it presently is not possible to design nor to prediet performance of dewatering facilities using traditional linearized parabolic filtration equation, that is, the specific resistance model because of theoretical and practical inadequacies of the concept. Limitations of the specific resistance model reflect the need to examine fundamental sludge properties and filtration behaviors affecting dewaterability. From this study, two major limitations of the specific resistance model were noted. First, specific resistance values are very dependent on the sludge concentration because of the variations of particle size distribution and cake clogging to occur when surface area mean diameter is less than $25{\mu}m$ for activated sludge, $18{\mu}m$ for water treatment plant sludge. Second, nonparabolic filtration behavior can result from cake clogging, caused by the migration of fine particles into the cake pores, accelated by skin effect with highly compressible sludges.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.2
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• pp.50-64
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• 1997

Life cycle assessment (LCA) on total sewage sludge treatment system from thickening to incineration and melting was performed for estimating global environmental impact as $CO_2$. In general, the life cycles of actual treatment facilities consist of construction, operation and dismantlement. In this study, the amount of $CO_2$ produced from both whole and each life cycle step of currently used unit sludge treatment processes were calculated by inventory analysis. In addition, in the all processes investigated in this study, individual $CO_2$ production unit (CPU), i.e. total produced $CO_2$ by treating a unit weight of sludge was also calculated. By using the CPU matrix of the unit processes, it was possible to simulate the $CO_2$ production for any type of complex-system as well as to trace a dominant cause of $CO_2$ production in each process. Four selected alternatives examined here, each involve the same disposal way but differ substantially in the $CO_2$ exhaust.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.37-46
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• 2012

The degradation characteristics of TCE by Ferrate(VI) oxidation have been studied. The degradation efficiency of TCE in aqueous solution was investigated at various pH values, Ferrate(VI) doses, initial concentrations of TCE and aqueous solution temperature values. GC-ECD was used to analyze TCE. The optimum conditions of TCE degradation were obtained pH 7.0 and $25^{\circ}C$ in aqueous solution. Also, the experimental results showed that TCE removal efficiency increased with the decrease of initial concentration of TCE. And intermediate products were identified by GC-MS techniques. Ethyl Chloride, Chloroform, Ethylene, 1,2-dichloroethane and 1,1,2-trichloroethane were identified as a reaction intermediate, and $Cl^-$ was identified as an end product.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.5
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• pp.659-668
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• 2012

In Korea, almost every water treatment plant suffers from seasonal problem of algae and turbidity which result from eutrophication and heavy rainfall. To relieve this problem, experimental investigation was performed to study the applicability of a floating-media and sand filter to preliminary water treatment in terms of algae and turbidity removal. Experimental results using pure-cultured algae influent showed that the shape of algae species as well as filtration velocity affects the removal efficiency. From the experiments using natural river water, it was concluded that algae removal is more sensitive to floating-media depth but turbidity more sensitive to sand depth. As the filtration velocity increased, the removal of turbidity decreased but that of algae was not affected. The floating-media and sand filter removed more than 30 % of TP, TN, turbidity, Chl-a and CODcr, and less than 20 % of DOC and $UV_{254}$.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1290-1291
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• 2015

원가대비 낮은 전기요금 현실화율에 따라 최근 3개년에 걸친 한전의 전력비 인상과 2015년 탄소배출권거래제 전면시행에 따른 추가적인 생산원가 상승요인은 산업현장 전반에 걸친 기업의 경쟁력 약화와 신규 투자의 위축으로 이어질 것으로 예측된다. 이 같은 시장 환경 속에서 생산원가 상승 잠재력 최소화에 도움이 되고자 본 논문을 작성하였다. 본 논문에서는 상하수도 사업장 전력비의 대부분을 차지하는 회전기계(펌핑시스템)의 최적화 방안에 대하여 연구하였으며, 전력사용량 절감을 위한 펌핑시스템 최적화 방안의 일환으로 인버터 최적운전 시뮬레이션 어플리케이션을 적용한 상하수도 사업장 펌핑시스템 특성 해석 사례에 대하여 살펴보고자 한다.